The present invention relates to substituted tricyclic thrombin receptor antagonists, pharmaceutical compositions containing them and their use in the treatment of diseases associated with thrombosis, atherosclerosis, restenosis, hypertension, angina pectoris, arrhythmia, heart failure, cerebral ischemia and cancer.
Thrombin is known to have a variety of activities in different cell types and thrombin receptors are known to be present in such cell types as human platelets, vascular smooth muscle cells, endothelial cells and fibroblasts. It is therefore expected that thrombin receptor antagonists will be useful in the treatment of thrombotic, inflammatory, atherosclerotic and fibroproliferative disorders, as well as other disorders in which thrombin and its receptor play a pathological role.
Thrombin receptor antagonists peptides have been identified based on structure-activity studies involving substututions of amino acids on thrombin receptors. In Bernatowicz et al, J. Med. Chem., 39 (1996), p. 4879-4887, tetra- and pentapeptides are disclosed as being potent thrombin receptor antagonists, for example N-trans-cinnamoyl-p-fluoroPhe-p-guanidinoPhe-Leu-Arg-NH.sub.2 and N-trans-cinnamoyl-p-fluoroPhe-p-guanidinoPhe-Leu-Arg-Arg-NH.sub.2. Peptide thrombin receptor anatgonists are also disclosed in WO 94/03479, published Feb. 17, 1994.
Himbacine, a piperidine alkaloid of the formula ##STR5##
has been identified as a muscarinic receptor antagonist. The total synthesis of (+)-himbacine is disclosed in Chackalamannil et al, J. Am.Chem Soc., 118 (1996), p. 9812-9813.